User's Tessitura is Giving "Invalid Credentials" for all Logins

Hello all,

I have a user who has Tessitura production on their machine. They were receiving errors on their end, so I removed and reinstalled Tessitura on their machine. Upon testing within their machine, all logins are giving "invalid credentials" error upon logging in. I have verified this error with my own login, which worked on my machine before and after testing on the users machine. Has anyone experienced this before?